Phenolic-hydroxyl-group-containing resins are used in adhesives, shaping materials, coating materials, photoresist materials, materials for producing epoxy resins, and curing agents for epoxy resins. Furthermore, such resins enable production of curing products having an excellent heat resistance and moisture resistance and are therefore widely used as curable compositions of which the main agents are phenolic-hydroxyl-group-containing resins themselves or as curing agents for epoxy or another resin in the electric and electronic fields, such as in sealing material of semiconductor devices and insulating materials of printed circuit boards.
In the field of photoresists, a variety of techniques for forming a resist pattern, which are used in different target areas on the basis of applications and functions, have been increasingly developed these days, which enhances and diversifies the demand performance of resin materials for the resist. The resin materials, for example, need to have a high developability that enables fine patterns to be accurately formed on highly integrated semiconductor devices at high efficiency. In addition, the resin materials need to impart properties, such as flexibility and durability, to cured products in the case of forming thick films; need to have resistance to dry etching and heat resistance in the case where they are used in resist underlayer films; and need to have toughness, such as conformability to substrates, as well as heat resistance in the case where they are used in permanent resist films.
Among phenolic-hydroxyl-group-containing resins, the resins most widely used in photoresists are cresol novolac resins; however, such resins do not satisfy the market demands for performance that has been enhanced and diversified as described above and do not have a sufficient heat resistance and developability (see Patent Literature 1).